stratisphereDenver is 1.609km or 5280ft above the ocean. Republic Plaza is a skyscraper in Denver, Colorado. Rising 728 feet (222 m),[3] the building currently stands as the tallest building in the city of Denver and the entire Rocky Mountain region of the United States.[2] It was built in 1984,[3] and contains 56 floors, the majority of which are used as office space. Republic Plaza currently stands as the 109th-tallest building in the United States.